Akt/Nrf2 Activated Upregulation of Heme Oxygenase-1 Involves in the Role of Rg1 Against Ferrous Iron-Induced Neurotoxicity in SK-N-SH Cells

Investigating the protective properties of Panax ginseng and its constituents against biotoxins and metal toxicity: a mechanistic review

Natural toxins are toxic substances produced by living microorganisms and cause harmful effects to other creatures, but not the organisms themselves. Based on the sources, they are classified into fungal, microbial, herbal, algae, and animal biotoxins. Metals, the oldest toxicants, are not created or destroyed by human industry as elements, just concentrated in the biosphere. An antidote can counteract the toxic effects of a drug or toxin or mitigate the adverse effects of a harmful substance. The potential antidote effects of Panax ginseng in organ toxicity have been proved by many scientific research projects. Herein, we are going to gather a comprehensive mechanistic review of the antidotal effects of ginseng and its main constituents against natural toxins and metal toxicity. In this regard, a literate search has been done in PubMed/Medline, Science Direct, and Scopus from 2000 until 2024. The gathered data showed the protective impacts of this golden plant and its secondary metabolites against aflatoxin, deoxynivalenol, three-nitro propionic acid, ochratoxin A, lipopolysaccharide, nicotine, aconite, domoic acid, α-synuclein, amyloid β, and glutamate as well as aluminum, cadmium, chrome, copper, iron, and lead. These antidotal effects occur by multi-functional mechanisms. It may be attributed to antioxidant, anti-inflammatory, and anti-apoptotic effects. Future research directions on the antidotal effects of ginseng against natural toxins and metal toxicity involve broadening the scope of studies to include a wider range of toxins and metals, exploring synergistic interactions with other natural compounds, and conducting more human clinical trials to validate the efficacy and safety of ginseng-based treatments.

Iron metabolism: An emerging therapeutic target underlying the anti-Alzheimer's disease effect of ginseng

Finding neuroprotective drugs with fewer side effects and more efficacy has become a major problem as the global prevalence of Alzheimer's disease (AD) rises. Natural drugs have risen to prominence as potential medication candidates. Ginseng has a long history of use in China, and it has a wide range of pharmacological actions that can help with neurological issues. Iron loaded in the brain has been linked to AD pathogenesis. We reviewed the regulation of iron metabolism and its studies in AD and explored how ginseng might regulate iron metabolism and prevent or treat AD. Researchers utilized network pharmacology analysis to identify key factive components of ginseng that protect against AD by regulating ferroptosis. Ginseng and its active ingredients may benefit AD by regulating iron metabolism and targeting ferroptosis genes to inhibit the ferroptosis process. The results present new ideas for ginseng pharmacological studies and initiatives for further research into AD-related drugs. To provide comprehensive information on the neuroprotective use of ginseng to modulate iron metabolism, reveal its potential to treat AD, and provide insights for future research opportunities.

Anti-fatigue effect of hypericin in a chronic forced exercise mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum perforatum L. is a traditional Chinese medicine used to sooth the liver, relieve depression, reduce body temperature, reduce sweating, and stimulate lactation. HP was extracted from Hypericum perforatum L.

AIM OF STUDY

The antifatigue effects of hypericin were assessed in a series of experiments.

MATERIALS AND METHODS

Six-to eight-week-old male ICR mice were raised in our lab. Mice were subjected to swimming training for 2 h, 6 days/week for 6 weeks. One hour prior to each swimming session, intraperitoneal injection of saline or HP (2 or 4 mg/kg) was performed.

RESULTS

Compared with the fatigue model control group, HP was found to significantly increase the swimming time in forced swimming tests. The molecular mechanisms underlying the antifatigue effects were further revealed by analysing energy metabolism, the oxidant-antioxidant system and the inflammatory response. HP normalized changes in BLA, LDH, BUN, and CK, LG in the liver. In addition, multiple assays have confirmed that HP improved the MDA, T-AOC, GSH-PX and SOD activity, and the relevant signalling pathways involved in the antifatigue effects were clarified. Furthermore, HP improves the expression of pro- and anti-inflammatory cytokines in skeletal muscle.

CONCLUSION

These results suggested that the anti-chronic fatigue effects of HP are likely achieved by normalizing energy metabolism and attenuating oxidative and inflammatory responses. Consequently, this study supports HP use in the clinic to alleviate chronic fatigue.

Nrf2 as a potential target for Parkinson's disease therapy

Parkinson's disease (PD) is a complex neurodegenerative disorder featuring both motor and nonmotor symptoms associated with a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Conventionally, PD treatment options have focused on dopamine replacement and provide only symptomatic relief. However, disease-modifying therapies are still unavailable. Mechanistically, genetic and environmental factors can produce oxidative stress which has been implicated as a core contributor to the initiation and progression of PD through the degeneration of dopaminergic neurons. Importantly, nuclear factor erythroid 2-related factor 2 (Nrf2) is essential for maintaining redox homeostasis by binding to the antioxidant response element which exists in the promoter regions of most genes coding for antioxidant enzymes. Furthermore, protein kinase C, mitogen-activated protein kinases, and phosphotidylinositol 3-kinase have been implicated in the regulation of Nrf2 activity during PD. Here, we review the evidence supporting the regulation of Nrf2 through Keap1-dependent and Keap1-independent mechanisms. We also address that targeting Nrf2 may provide a therapeutic option to mitigate oxidative stress-associated PD. Finally, we discuss currently known classes of small molecule activators of Nrf2, including Nrf2-activating compounds in PD.

α-Lipoic acid alleviates ferroptosis in the MPP+ -induced PC12 cells via activating the PI3K/Akt/Nrf2 pathway

Parkinson's disease (PD) is a typical neurodegenerative disease. α-Lipoic acid (α-LA) can reduce the incidence of neuropathy. The present study explored the role and mechanism of α-LA in 1-methyl-4-phenylpyridinium (MPP⁺ )-induced cell model of PD. The PD model was induced via treating PC12 cells with MPP⁺  at different concentrations. MPP⁺  and α-LA effects on PC12 cells were assessed from cell viability and ferroptosis. Cell viability was detected using the cell counting kit-8 assay. Malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), iron, reactive xygen species (ROS), and glutathione (GSH) concentrations, and ferroptosis-related protein SLC7A11 and GPx4 expressions were used for ferroptosis evaluation. p-PI3K, p-Akt, and nuclear factor erythroid 2-related factor 2 (Nrf2) protein levels were detected. The PI3K/Akt/Nrf2 pathway inhibitors were applied to verify the role of the PI3K/Akt/Nrf2 pathway in α-LA protection against MPP⁺ -induced decreased cell viability and ferroptosis. MPP⁺ -reduced cell viability and induced ferroptosis as presented by increased MDA, 4-HNE, iron, and ROS concentrations, and reduced levels of GSH and ferroptosis marker proteins (SLC7A11 and GPx4). α-LA attenuated MPP⁺ -induced cell viability decline and ferroptosis. The PI3K/Akt/Nrf2 pathway was activated after α-LA treatment. Inhibiting the PI3K/Akt/Nrf2 pathway weakened the protection of α-LA against MPP⁺  treatment. We highlighted that α-LA alleviated MPP⁺ -induced cell viability decrease and ferroptosis in PC12 cells via activating the PI3K/Akt/Nrf2 pathway.

Korean Red Ginseng alleviates dehydroepiandrosterone-induced polycystic ovarian syndrome in rats via its antiinflammatory and antioxidant activities

BACKGROUND

Beneficial effects of Korean Red Ginseng (KRG) on polycystic ovarian syndrome (PCOS) remains unclear.

METHODS

We examined whether pretreatment (daily from 2 hours before PCOS induction) with KRG extract in water (KRGE; 75 and 150 mg/kg/day, p.o.) could exert a favorable effect in a dehydroepiandrosterone (DHEA)-induced PCOS rat model.

RESULTS

Pretreatment with KRGE significantly inhibited the elevation of body and ovary weights, the increase in number and size of ovarian cysts, and the elevation of serum testosterone and estradiol levels induced by DHEA. Pretreatment with KRGE also inhibited macrophage infiltration and enhanced mRNA expression levels of chemokines [interleukin (IL)-8, monocyte chemoattractant protein-1), proinflammatory cytokines (IL-1β, IL-6), and inducible nitric oxide synthase in ovaries induced by DHEA. It also prevented the reduction in mRNA expression of growth factors (epidermal growth factor, transforming growth factor-beta (EGF, TGF-β)) related to inhibition of the nuclear factor kappa-light-chain-enhancer of activated B cell pathway and stimulation of the nuclear factor erythroid-derived 2-related factor 2 pathway. Interestingly, KRGE or representative ginsenosides (Rb1, Rg1, and Rg3(s)) inhibited the activity of inflammatory enzymes cyclooxygenase-2 and iNOS, cytosolic p-IkB, and nuclear p-nuclear factor kappa-light-chain-enhancer of activated B in lipopolysaccharide-induced RAW264.7 cells, whereas they increased nuclear factor erythroid-derived 2-related factor 2 nuclear translocation.

CONCLUSION

These results provide that KRGE could prevent DHEA-induced PCOS via antiinflammatory and antioxidant activities. Thus, KRGE may be used in preventive and therapeutic strategies for PCOS-like symptoms.

Ginseng and heme oxygenase-1: The link between an old herb and a new protective system

Ginseng is an ancient herb, belonging to Asian traditional medicine, that has been considered as a restorative to enhance vitality for centuries. It has been demonstrated that the antioxidant action of ginseng may be mediated through activation of different cellular signaling pathways involving the heme oxygenase (HO) system. Several compounds derived from ginseng have been studied for their potential role in brain, heart and liver protection, and the Nrf2 pathway seems to be the most affected by these natural molecules to exert this effect. Ginseng is also popularly used in cancer patients therapy for the demonstrated capability to defend tissues from chemotherapy-induced damage. Reported results suggest that the effect of ginseng is primarily associated with ROS scavenging, mainly exerted through the activation of Nrf2 pathway, and the consequent induction of HO-1 levels. This review aims to discuss the connection between the antioxidant properties of ginseng and the activation of the HO system, as well as to outline novel therapeutic applications of this medicinal plant to human health.

Research Progress in Understanding the Relationship Between Heme Oxygenase-1 and Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a fatal acute cerebrovascular disease, with a high morbidity and mortality. Following ICH, erythrocytes release heme and several of its metabolites, thereby contributing to brain edema and secondary brain damage. Heme oxygenase is the initial and rate-limiting enzyme of heme catabolism, and the expression of heme oxygenase-1 (HO-1) is rapidly induced following acute brain injury. As HO-1 exerts it effects via various metabolites, its role during ICH remains complex. Therefore, in-depth studies regarding the role of HO-1 in secondary brain damage following ICH may provide a theoretical basis for neuroprotective function after ICH. The present review aims to summarize recent key studies regarding the effects of HO-1 following ICH, as well as its influence on ICH prognosis.

Neuroprotective effects of genistein on SH-SY5Y cells overexpressing A53T mutant α-synuclein

Genistein, a potent antioxidant compound, protects dopaminergic neurons in a mouse model of Parkinson's disease. However, the mechanism underlying this action remains unknown. This study investigated human SH-SY5Y cells overexpressing the A53T mutant of α-synuclein. Four groups of cells were assayed: a control group (without any treatment), a genistein group (incubated with 20 μM genistein), a rotenone group (treated with 50 μM rotenone), and a rotenone + genistein group (incubated with 20 μM genistein and then treated with 50 μM rotenone). A lactate dehydrogenase release test confirmed the protective effect of genistein, and genistein remarkably reversed mitochondrial oxidative injury caused by rotenone. Western blot assays showed that BCL-2 and Beclin 1 levels were markedly higher in the genistein group than in the rotenone group. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling revealed that genistein inhibited rotenone-induced apoptosis in SH-SY5Y cells. Compared with the control group, the expression of NFE2L2 and HMOX1 was significantly increased in the genistein + rotenone group. However, after treatment with estrogen receptor and NFE2L2 channel blockers (ICI-182780 and ML385, respectively), genistein could not elevate NFE2L2 and HMOX1 expression. ICI-182780 effectively prevented genistein-mediated phosphorylation of NFE2L2 and remarkably suppressed phosphorylation of AKT, a protein downstream of the estrogen receptor. These findings confirm that genistein has neuroprotective effects in a cell model of Parkinson's disease. Genistein can reduce oxidative stress damage and cell apoptosis by activating estrogen receptors and NFE2L2 channels.

Emerging signals modulating potential of ginseng and its active compounds focusing on neurodegenerative diseases

Common features of neurodegenerative diseases (NDDs) include progressive dysfunctions and neuronal injuries leading to deterioration in normal brain functions. At present, ginseng is one of the most frequently used natural products. Its use has a long history as a cure for various diseases because its extracts and active compounds exhibit several pharmacological properties against several disorders. However, the pathophysiology of NDDs is not fully clear, but researchers have found that various ion channels and specific signaling pathways might have contributed to the disease pathogenesis. Apart from the different pharmacological potentials, ginseng and its active compounds modulate various ion channels and specific molecular signaling pathways related to the nervous system. Here, we discuss the signal modulating potential of ginseng and its active compounds mainly focusing on those relevant to NDDs.

Multitarget effects of Korean Red Ginseng in animal model of Parkinson's disease: antiapoptosis, antioxidant, antiinflammation, and maintenance of blood-brain barrier integrity

Background

Ginsenosides are the main ingredients of Korean Red Ginseng. They have extensively been studied for their beneficial value in neurodegenerative diseases such as Parkinson's disease (PD). However, the multitarget effects of Korean Red Ginseng extract (KRGE) with various components are unclear.

Methods

We investigated the multitarget activities of KRGE on neurological dysfunction and neurotoxicity in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)–induced mouse model of PD. KRGE (37.5 mg/kg/day, 75 mg/kg/day, or 150 mg/kg/day, per os (p.o.)) was given daily before or after MPTP intoxication.

Results

Pretreatment with 150 mg/kg/day KRGE produced the greatest positive effect on motor dysfunction as assessed using rotarod, pole, and nesting tests, and on the survival rate. KRGE displayed a wide therapeutic time window. These effects were related to reductions in the loss of tyrosine hydroxylase–immunoreactive dopaminergic neurons, apoptosis, microglial activation, and activation of inflammatory factors in the substantia nigra pars compacta and/or striatum after MPTP intoxication. In addition, pretreatment with KRGE activated the nuclear factor erythroid 2–related factor 2 pathways and inhibited phosphorylation of the mitogen-activated protein kinases and nuclear factor-kappa B signaling pathways, as well as blocked the alteration of blood–brain barrier integrity.

Conclusion

These results suggest that KRGE may effectively reduce MPTP-induced neurotoxicity with a wide therapeutic time window through multitarget effects including antiapoptosis, antiinflammation, antioxidant, and maintenance of blood–brain barrier integrity. KRGE has potential as a multitarget drug or functional food for safe preventive and therapeutic strategies for PD.

Metal ions influx is a double edged sword for the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is a common form of dementia in aged people, which is defined by two pathological characteristics: β-amyloid protein (Aβ) deposition and tau hyperphosphorylation. Although the mechanisms of AD development are still being debated, a series of evidence supports the idea that metals, such as copper, iron, zinc, magnesium and aluminium, are involved in the pathogenesis of the disease. In particular, the processes of Aβ deposition in senile plaques (SP) and the inclusion of phosphorylated tau in neurofibrillary tangles (NFTs) are markedly influenced by alterations in the homeostasis of the aforementioned metal ions. Moreover, the mechanisms of oxidative stress, synaptic plasticity, neurotoxicity, autophagy and apoptosis mediate the effects of metal ions-induced the aggregation state of Aβ and phosphorylated tau on AD development. More importantly, imbalance of these mechanisms finally caused cognitive decline in different experiment models. Collectively, reconstructing the signaling network that regulates AD progression by metal ions may provide novel insights for developing chelators specific for metal ions to combat AD.

Panax ginseng exerts antidepressant-like effects by suppressing neuroinflammatory response and upregulating nuclear factor erythroid 2 related factor 2 signaling in the amygdala

Background

Depression is one of the most commonly diagnosed neuropsychiatric diseases, but the underlying mechanism and medicine are not well-known. Although Panax ginseng has been reported to exert protective effects in various neurological studies, little information is available regarding its antidepressant effects.

Methods

Here, we examined the antidepressant effect and underlying mechanism of P. ginseng extract (PGE) in a chronic restraint stress (CRS)-induced depression model in mice.

Results

Oral administration of PGE for 14 d decreased immobility (depression-like behaviors) time in forced swim and tail suspended tests after CRS induction, which corresponded with attenuation of the levels of serum adrenocorticotropic hormone and corticosterone, as well as attenuated c-Fos expression in the amygdala. PGE enhanced messenger RNA expression level of brain-derived neurotrophic factor but ameliorated microglial activation and neuroinflammation (the level of messenger RNA and protein expression of cyclooxygenase-2 and inducible nitric oxide synthase) in the amygdala of mice after CRS induction. Interestingly, 14-d treatment with celecoxib, a selective cyclooxygenase-2 inhibitor, and N_ω-nitro-L-arginine methyl ester hydrochloride, a selective inducible nitric oxide synthase inhibitor, attenuated depression-like behaviors after CRS induction. Additionally, PGE inhibited the upregulation of the nuclear factor erythroid 2 related factor 2 and heme oxygenase-1 pathways.

Conclusion

Taken together, our findings suggest that PGE exerts antidepressant-like effect of CRS-induced depression by antineuroinflammatory and antioxidant (nuclear factor erythroid 2 related factor 2/heme oxygenase-1 activation) activities by inhibiting the hypothalamo-pituitary-adrenal axis mechanism. Further studies are needed to evaluate the potential of components of P. ginseng as an alternative treatment of depression, including clinical trial evaluation.

Mountain-Cultivated Ginseng Attenuates Phencyclidine-Induced Abnormal Behaviors in Mice by Positive Modulation of Glutathione in the Prefrontal Cortex of Mice

Escalating evidence indicates that ginseng treatment protects against psychotoxic behaviors and memory impairment. Although the underlying mechanism of schizophrenia remains elusive, recent investigations proposed that downregulation of glutathione (GSH) can be involved in the pathogenesis of this disorder. Since little is known about the effects of ginseng in a schizophrenia-like animal model, we selected mountain-cultivated ginseng (MG) from a variety of ginseng extracts to investigate the effect of ginseng on the psychosis induced by phencyclidine (PCP) in mice. PCP (10 mg/kg/day, s.c.) was administered for 14 consecutive days. Novel object recognition, forced swimming, and social interaction tests were performed during the withdrawal period of 7 days. In addition, behavioral sensitization to an acute challenge of PCP was evaluated. The parameters of the GSH-dependent system in the prefrontal cortex (PFC) were examined. MG (200 mg/kg, i.p./day) or antipsychotic clozapine (10 mg/kg, p.o./day) was administered for seven consecutive days after the final PCP treatment. PCP significantly produced abnormal behaviors, followed by increases in Nrf2 nuclear translocation, its DNA binding activity, and glutamate-cysteine ligase (GCL) mRNA expression in the PFC. PCP treatment significantly decreased GSH/glutathione disulfide (GSSG) ratio and glutathione peroxidase (GPx) activity. MG significantly attenuated abnormal behaviors and the decreases in GSH/GSSG ratio and GPx activity induced by PCP. MG attenuated the increases in Nrf2 activity and GCL expression caused by PCP. The protective potentials of MG were comparable to those of clozapine. MG ameliorates PCP-induced schizophrenia-like psychosis in mice through the positive modulation of the glutathione system.

Protective effects of ginseng on neurological disorders

Ginseng (Order: Apiales, Family: Araliaceae, Genus: Panax) has been used as a traditional herbal medicine for over 2000 years, and is recorded to have antianxiety, antidepressant and cognition enhancing properties. The protective effects of ginseng on neurological disorders are discussed in this review. Ginseng species and ginsenosides, and their intestinal metabolism and bioavailability are briefly introduced. This is followed by molecular mechanisms of effects of ginseng on the brain, including glutamatergic transmission, monoamine transmission, estrogen signaling, nitric oxide (NO) production, the Keap1/Nrf2 adaptive cellular stress pathway, neuronal survival, apoptosis, neural stem cells and neuroregeneration, microglia, astrocytes, oligodendrocytes and cerebral microvessels. The molecular mechanisms of the neuroprotective effects of ginseng in Alzheimer’s disease (AD) including β-amyloid (Aβ) formation, tau hyperphosphorylation and oxidative stress, major depression, stroke, Parkinson’s disease and multiple sclerosis are presented. It is hoped that this discussion will stimulate more studies on the use of ginseng in neurological disorders.

Myricitrin attenuates endothelial cell apoptosis to prevent atherosclerosis: An insight into PI3K/Akt activation and STAT3 signaling pathways

Blood vessel endothelial dysfunction induced by oxidized low-density lipoprotein (ox-LDL) has been implicated in the pathogenesis of atherosclerosis and vasculopathy. The ox-LDL-elicited reactive oxygen species (ROS) release has been assumed to serve a critical function in endothelial damage. Myricitrin (from Myrica cerifera) is a natural antioxidant that has strong anti-oxidative, anti-inflammatory, and anti-nociceptive activities. However, the protective effect of myricitrin on ROS-induced endothelial cell injury and its related molecular mechanisms have never been investigated. This study demonstrates that myricitrin can inhibit ox-LDL-induced endothelial apoptosis and prevent plaque formation at an early stage in an atherosclerotic mouse model. The administration of myricitrin in vivo decreases the thickness of the vascular wall in the aortic arch of ApoE-/- mice. In vitro study shows that ox-LDL-induced human umbilical vein endothelial cell apoptosis can be reduced upon receiving myricitrin pre-treatment. Treatment with myricitrin significantly attenuated ox-LDL-induced endothelial cell apoptosis by inhibiting LOX-1 expression and by increasing the activation of the STAT3 and PI3K/Akt/eNOS signaling pathways. At the same time, our result demonstrates that myricitrin treatment optimizes the balance of pro/anti-apoptosis proteins, including Bax, Bad, XIAP, cIAP-2, and survivin. Our study suggests that myricitrin treatment can effectively protect cells from ox-LDL-induced endothelial cell apoptosis, which results in reduced atherosclerotic plaque formation. This result indicates that myricitrin can be used as a drug candidate for the treatment of cardiovascular diseases.

Ginseng: a promising neuroprotective strategy in stroke

Ginseng is one of the most widely used herbal medicines in the world. It has been used in the treatment of various ailments and to boost immunity for centuries; especially in Asian countries. The most common ginseng variant in traditional herbal medicine is ginseng, which is made from the peeled and dried root of Panax Ginseng. Ginseng has been suggested as an effective treatment for a vast array of neurological disorders, including stroke and other acute and chronic neurodegenerative disorders. Ginseng’s neuroprotective effects are focused on the maintenance of homeostasis. This review involves a comprehensive literature search that highlights aspects of ginseng’s putative neuroprotective effectiveness, focusing on stroke. Attenuation of inflammation through inhibition of various proinflammatory mediators, along with suppression of oxidative stress by various mechanisms, including activation of the cytoprotective transcriptional factor Nrf2, which results in decrease in reactive oxygen species, could account for its neuroprotective efficacy. It can also prevent neuronal death as a result of stroke, thus decreasing anatomical and functional stroke damage. Although there are diverse studies that have investigated the mechanisms involved in the efficacy of ginseng in treating disorders, there is still much that needs to be clarified. Both in vitro and in vivo studies including randomized controlled clinical trials are necessary to develop in-depth knowledge of ginseng and its practical applications.

Arctigenin enhances swimming endurance of sedentary rats partially by regulation of antioxidant pathways

AIM

Arctigenin, a phenylpropanoid dibenzylbutyrolactone lignan found in traditional Chinese herbs, has been determined to exhibit a variety of pharmacological activities, including anti-tumor, anti-inflammation, neuroprotection, and endurance enhancement. In the present study, we investigated the antioxidation and anti-fatigue effects of arctigenin in rats.

METHODS

Rat L6 skeletal muscle cell line was exposed to H2O2 (700 μmol/L), and ROS level was assayed using DCFH-DA as a probe. Male SD rats were injected with arctigenin (15 mg·kg(-1)·d(-1), ip) for 6 weeks, and then the weight-loaded forced swimming test (WFST) was performed to evaluate their endurance. The levels of antioxidant-related genes in L6 cells and the skeletal muscles of rats were analyzed using real-time RT-PCR and Western blotting.

RESULTS

Incubation of L6 cells with arctigenin (1, 5, 20 μmol/L) dose-dependently decreased the H2O2-induced ROS production. WFST results demonstrated that chronic administration of arctigenin significantly enhanced the endurance of rats. Furthermore, molecular biology studies on L6 cells and skeletal muscles of the rats showed that arctigenin effectively increased the expression of the antioxidant-related genes, including superoxide dismutase (SOD), glutathione reductase (Gsr), glutathione peroxidase (GPX1), thioredoxin (Txn) and uncoupling protein 2 (UCP2), through regulation of two potential antioxidant pathways: AMPK/PGC-1α/PPARα in mitochondria and AMPK/p53/Nrf2 in the cell nucleus.

CONCLUSION

Arctigenin efficiently enhances rat swimming endurance by elevation of the antioxidant capacity of the skeletal muscles, which has thereby highlighted the potential of this natural product as an antioxidant in the treatment of fatigue and related diseases.

Attenuation of Aβ25-35-induced parallel autophagic and apoptotic cell death by gypenoside XVII through the estrogen receptor-dependent activation of Nrf2/ARE pathways

Amyloid-beta (Aβ) has a pivotal function in the pathogenesis of Alzheimer's disease. To investigate Aβ neurotoxicity, we used an in vitro model that involves Aβ25-35-induced cell death in the nerve growth factor-induced differentiation of PC12 cells. Aβ25-35 (20μM) treatment for 24h caused apoptotic cell death, as evidenced by significant cell viability reduction, LDH release, phosphatidylserine externalization, mitochondrial membrane potential disruption, cytochrome c release, caspase-3 activation, PARP cleavage, and DNA fragmentation in PC12 cells. Aβ25-35 treatment led to autophagic cell death, as evidenced by augmented GFP-LC3 puncta, conversion of LC3-I to LC3-II, and increased LC3-II/LC3-I ratio. Aβ25-35 treatment induced oxidative stress, as evidenced by intracellular ROS accumulation and increased production of mitochondrial superoxide, malondialdehyde, protein carbonyl, and 8-OHdG. Phytoestrogens have been proved to be protective against Aβ-induced neurotoxicity and regarded as relatively safe targets for AD drug development. Gypenoside XVII (GP-17) is a novel phytoestrogen isolated from Gynostemma pentaphyllum or Panax notoginseng. Pretreatment with GP-17 (10μM) for 12h increased estrogen response element reporter activity, activated PI3K/Akt pathways, inhibited GSK-3β, induced Nrf2 nuclear translocation, augmented antioxidant responsive element enhancer activity, upregulated heme oxygenase 1 (HO-1) expression and activity, and provided protective effects against Aβ25-35-induced neurotoxicity, including oxidative stress, apoptosis, and autophagic cell death. In conclusion, GP-17 conferred protection against Aβ25-35-induced neurotoxicity through estrogen receptor-dependent activation of PI3K/Akt pathways, inactivation of GSK-3β and activation of Nrf2/ARE/HO-1 pathways. This finding might provide novel insights into understanding the mechanism for neuroprotective effects of phytoestrogens or gypenosides.

Ginsenoside Rg1 reduces toxicity of fine particulate matter on human alveolar epithelial cells: a preliminary observation

Fine particulate matter (PM2.5) is a significant environmental pollutant responsible for a number of human diseases. Ginsenoside Rg1 (Rg1) is likely to have the potential to relieve PM2.5‑induced cell injury. The present study is designed to preliminarily observe the harmful effect of PM2.5 and the protective effect of Rg1 against PM2.5 on human A549 lung epithelial cells in vitro. The cytotoxic effects of the PM2.5 or Rg1 on A549 cells were measured by means of cell viability, and then exposure concentration of PM2.5 and pretreatment concentration of Rg1 used in the following assays were established. The A549 cells were pretreated with Rg1 for 1 h and then exposed to PM2.5 for 24 h. The levels of lactate dehydrogenase (LDH) in the cell culture supernatant and malondialdehyde (MDA) within the cells were assayed. The present results revealed that 200‑1,200 µg/ml of PM2.5 decreased the viability of A549 cells significantly in a concentration‑dependent manner; however, 50‑400 µg/ml of Rg1 had no significant effect. Pretreatment with 100, 200 or 400 µg/ml Rg1 significantly diminished the 200 µg/ml PM2.5‑induced A549 cell viability and decreased LDH leakage and MDA generation in a concentration‑dependent manner. These results indicated that PM2.5 induced cell injury and Rg1, antagonized PM2.5‑induced cell injury to a certain extent.

P90RSK and Nrf2 Activation via MEK1/2-ERK1/2 Pathways Mediated by Notoginsenoside R2 to Prevent 6-Hydroxydopamine-Induced Apoptotic Death in SH-SY5Y Cells

6-Hydroxydopamine (6-OHDA) is known to contribute to neuronal death in Parkinson's disease. In this study, we found that the preincubation of SH-SY5Y cells for 24 h with 20  μ M notoginsenoside R2 (NGR2), which is a newly isolated notoginsenoside from Panax notoginseng, showed neuroprotective effects against 6-OHDA-induced oxidative stress and apoptosis. NGR2 incubation successively resulted in the activation of P90RSK, inactivation of BAD, and inhibition of 6-OHDA-induced mitochondrial membrane depolarization, thus preventing the mitochondrial apoptosis pathway. NGR2 incubation also led to the activation of Nrf2 and subsequent activity enhancement of phase II detoxifying enzymes, thus suppressing 6-OHDA-induced oxidative stress, and these effects could be removed by Nrf2 siRNA. We also found that the upstream activators of P90RSK and Nrf2 were the MEK1/2-ERK1/2 pathways but not the JNK, P38, or PI3K/Akt pathways. Interestingly, NGR2 incubation could also activate MEK1/2 and ERK1/2. Most importantly, NGR2-mediated P90RSK and Nrf2 activation, respective downstream target activation, and neuroprotection were reversed by the genetic silencing of MEK1/2 and ERK1/2 by using siRNA and PD98059 application. These results suggested that the neuroprotection elicited by NGR2 against 6-OHDA-induced neurotoxicity was associated with NGR2-mediated P90RSK and Nrf2 activation through MEK1/2-ERK1/2 pathways.